1. Field of the Invention
The present invention relates to a signal transceiver apparatus and system, and particularly to a wired signal transceiver apparatus and system.
2. Description of Related Art
In recent years, due to advances in technology of semiconductor fabrication, manufacturing electronic products that are light, thin, small and having powerful functions has become a main issue in product designs of the modern electronic products. Regarding requirements in such aspects, engineers often use technologies that dispose a great number of circuits on a single chip and methods of so-called system on chip (SOC) to cope.
However, no matter using what sort of the above technologies, problems of impedance mismatch of signal transmission between different functional circuits are inevitably faced. Please refer to the following FIG. 1, which is a schematic diagram showing a conventional signal transceiver system 100. A signal transceiver system 100 includes two signal transceiver apparatuses 110 and 120, and the signal transceiver apparatuses 110 and 120 respectively belong to different chips. In the signal transceiver apparatus 110, a ratio of current values transmitted by current sources I1, I2 and I3 is 1:0.5:0.25; similarly, a ratio of current values transmitted by current sources I4, I5 and I6 is 1:0.5:0.25. Diodes D1, D2, D3 and D4 are used to ensure that flowing directions of the currents are unidirectional, and transistors M1, M2, M3 and M4 function at a linear region, playing roles of voltage-controlled resistors being controlled by a voltage VR. Data signals to be transmitted are respectively transmitted to input ends IN1 and IN2 of the signal transceiver apparatuses 110 and 120. Switches SW1 and SW2 are respectively controlled by inverse signals of the input ends IN1 and IN2.
The signal transceiver apparatuses 110 and 120 tune currents flowing through the transistors M1, M2, M3 and M4 by on or off of transistors M5 and M6 used as switches in cooperation with on or off of the switches SW1 and SW2, thereby generating different voltages. Comparators CMP1 and CMP2 are further used to compare the above voltages, and received data signals are respectively generated at output ends O1 and O2.
This kind of signal transceiver system 100 uses relations between each of the resistors (including the voltage-controlled resistors formed by the transistors M1, M2, M3 and M4 and impedance of a wire L) in the system to complete a transceiver action, so that the voltage VR used to control the voltage-controlled resistors may be appropriately tuned. Such a tuning mechanism requires a resistor externally connected to an exterior of the chip for completion, thereby intangibly increasing areas and cost of the circuit. Moreover, the signal transceiver system 100 is a unidirectional transceiver device, thereby being more sensitive towards interference by noise, and transceiving qualities of the data signals also need to be improved.